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Patented oct. is, was 2,133,501

PROCESS FOR THE PRODUCTION OF ZEIN Lloyd C. Swallen, Pekin, BL, assignor, by mesne assignments, to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application May 8, 1935, Serial No. 20,402 Renewed January 3, 1938 6 Claims. (Cl. 87-28) My invention relates to an improved process alcohols with other organic solvents. The exfor obtaining concentrated solutions of zein from traction step may be carried out according to any the mixed proteins of maize. More specifically, known procedure, but if the zein is to be used my invention relates to a process for obtaining for plastic purposes, I prefer to employ the zein in concentrated solution having reduced oil p ocess disclosed in my copending application 5 and colorcontent and unaltered plasticity. Ser. No. 20,401, filed May 8, 1935. Accordin It has long been known that zein could be to this process, the extraction is effected at temextracted from maize meal or from mixed maize peratures below 70 C. and preferably from proteins such as gluten meal by extraction with 55-65 C., and at hydrogen ion concentrations 10 aqueous alcoholic solvents. Various processes for such that the pH of the final extract is above 6.0 10 concentrating and purifying the resulting exand preferably falls within the range 6.0-7.0. tracts have also been known. The processes used Any suitable apparatus may be employed, as for in the past, however, have been designed priexample, apercolator, and the process may be marily for laboratory preparations and I have carried out either by the batch e od, t e found that such processes are not suitable for counte'rcurrent method, ora combination of these 15 producing purified zein for use in the preparation two. of plastics. For this purpose the physical nature The extract obtained in the first step of the of the product is extremely important, in addiprocess is next subjected to concentration in tion to its chemical properties or its adhesive order to minimize the volumes handled in later properties. It is necessary that the material be stages of the process and to facilitate the subsein a form which is adapted to plastic flow at suit- .quent extraction step. The concentration may able temperatures in the presence of curing agents be effected by any means suitable for handling. such as formaldehyde. I have found that the protein solutions, but I prefer simply to subjectprior processes have either altered the plasticity the solution to vacuum distillation. The degree of the zein to an undesirable extent or have inof concentration to be secured in this step of the 25 volved the treatment of such dilute solutions as process will'clepend to some extent upon the water to. render the process impractical from a comcontent of the original extraction medium. Inmercial standpoint. creased water content increases the danger of I have now discovered a process which obviprecipitation in this step, but a safe limit of ates all of these prior difficulties. According to concentration can readily be determined by a 30 my present invention, the zein is progressively simple preliminary experiment. If the preferred concentrated in each step of the process with, water content of 78% in the original extraction consequent minimized handling costs and mini medium is employed, I have found that the solumized solvent losses. Also, the zein is maintion may then be concentrated to any extent .35 tained in solution throughout the entire process compatible with subsequent mechanical handling.

so that its plasticity is not impaired by changes For example, after concentration to 30% zein in state such as precipitation or gelling. My content, in which case the percentage of water process comprises, briefly, extracting the proteinin the solvent mixture may be as high as 20% aceous material with an aqueous alcoholic solthe material will be found to havea consistency .10 vVent mixture of low water content, concentrating of thick molasses. This may be handled satis- 40 the resulting extract, and treating the concenfactorily in most apparatus and constitutes a detrated extract with an alcohol-miscible organic sirable degree of concentration from the standsolvent for oil and coloring matter which is a pointof efii'cient solvent recovery. non-solvent for zein, whereby the zein is sepa-' The concentrated solution obtained as derated in an alcoholic solution of increased conscribed above is next subjected to treatment with 45 centration and oil and coloring matter are rea solvent for maize oil and coloring matter, moved. I whichis at least partially miscible with alcohol,

The extraction step is effected by means of and which is a non-solvent for zein. I have an aqueousalcoholic solvent containing about found that toluol is quite satisfactory for this 5-10% or more water and preferably 745%. A purpose, although various other materials may 50 concentrationoi water up to 20% or more may be employed. Other'aromatic hydrocarbons such be employed if the zein tolerance of the particular as benzol and-xylol may be used, and chlorinated solution is not exceeded. The solvent may comhydrocarbons such as carbon tetrachloride will prise pure aqueous ethyl alcohol or other suitable also be found to be satisfactory. Aliphatic hysolvents such as methyl alcohol or mixtures of drocarbons such as petroleum ether and the like 55 may be employed, but these are somewhat deficient in miscibility with ethyl alcohol, when such is the zein solvent used, as well as in solvent power for coloring matter, and will usually necessitate an increased number of extractions. The solvent employed is added directly to the concentrated zein solution and the mixture is thoroughly agitated and then allowed to settle. The mixture will be found to separate into two layers, the one comprising an alcoholic zein solution, and the other a solvent layer containing a portion of the alcohol and a substantial amount of the oil and coloring matter of the original solution. These layers may readily be separated by the use of a siphon or simply by decanting the upper layer. Depending upon the nature of the oil solvent and the relative amount employed it will be possible to regulate within certain limits the concentration of zein in the alcohol layer. Using pure toluol as the oil solvent, in an amount sufllcient to remove the bulk of the oil and coloring matter, the concentration of zein in the alcohol layer will be substantially increased. Further concentration of zein and further extraction of oil and coloring matter may be obtained by repeating this process.

The amount of solvent utilized for each extraction is not critical so long as it is sufllcient to eifect a complete separation of the two layers and is insufficient to precipitate the zein in doughllke form. When employing pure aqueous alcohol in the first extraction step of my process, I find that the addition of a volume of toluol or other color solvent equal to the volume of the concentrated alcoholic zein solution is quite satisfactory. The optimum amount for each extraction and the optimum number of color extractions to be made will, of 'course, depend upon economic considerations and upon the desired purity of the product. For commercial operation it 'would be desirable to modify the extraction process to utilize secondary extracts from previous batches as initial extracting media for new material, or to utilize a strictly countercurrent system.

After the final extraction with the color solvent and the separation of the solvent layer, the zein is obtained in a concentrated solution suitable for'treatment to obtain the zein in a solid state.

The material will be found to have unaltered plasticity and to have an oil and color content suiilciently reduced to be suitable for use in the pre aration of plastics. cen ration step is carried to a concentration of 30% zein or higher, the final solution, after treatment with the color solvent, will be found to be in the form of a thick paste suitable for treatment in any known manner to recover the solid zein. It may thus be seen that my process secures the ultimate concentration of zein while still maintaining the material in solution and preventing reduction of its'plas'ticity. This is accomplished in a minimum number of operations which serve at the same time to purify the materlal and reduce its oil and solor content. These advantages are outstanding from the standpoint of a commercially feasible process for obtaining a protein in a suitable physical form for use in plastic production.

My invention may further be illustrated by the following specific example: 100 lbs. of gluten meal ground to pass an 8 mesh screen but not a 20 mesh screen was'mixed with 35 gallons of hot 93% ethyl alcohol in a suitable vessel and gently agitated for a period of 2 hours.

If the intermediate con- The temperature after first mixing was approximately 60 C. The alcohol solution contained 2 liters of 6.5 N

sodium hydroxide, giving an initial pH of 8.0 anda final pH of approximately 6.5. After the 2 hour extraction period, the alcoholic extract was decanted from the meal and distilled under vacuum at 35-40 C. vapor temperature for a period of approximately 2 hours, thus reducing the volume to approximately 9 gallons. The concentrated extract was then stirred with 13 gallons of toluol and, after allowing it to settle, the supernatant solvent layer was decanted. Four additional extractions with equal volumes of toluol were then made, and after the final separation, the zein was obtained in an alcoholic solution having the consistency of a thick paste. After recovery in solid form the zein was found .to have unaltered plasticity and to have a satisfactory light-color and low oil content. When made into a plastic, the resulting product was found to be a clear light-colored hard material having satisfactory toughness and elasticity and a transverse strength of 11,500 lbs. per sq. inch.

It will be understood, of course, that in commercial operation of the process of the above example the original zein extraction would be followed by additional extractions, or washes, and the wash solutions would be utilized for preliminary extractions of subsequent batches. Likewise, the zein extraction and also the subsequent color extraction could be carried out according to strictly countercurrent methods. This example is illustrative only and is not to be construed as limiting the scope of my invention. In general, it may be said that any equivalents or any modifications of procedure which would naturally occur to one skilled in the art may be employed without departing from the scope of my invention.

My invention now having been described, what I claim is:

1. Process of removing oil and color from an aqueous alcohol solution of zein which comprises treating said solution with a volatile aromatic hydrocarbon solvent for maize-oil and coloring matter, in such quantity that the material is separated into two liquid layers, the lower containing zein, its solvent and, some of the oil solvent, the upper layer containing oil, coloring matter and zein and oil solvents; and separating said layers one from the other.

2. Process of removing oil and color from an aqueous alcoholic solution of zein containing at least of water which comprises: treating said solution with a volatile aromatic hydrocarbon solvent for maize-oil and coloring matter in such quantity that the material is separated into two liquid layers, the lower containing zein, alcohol and some of the oil solvent, the upper layer containing oil, coloring matter, alcohol and oil solvent; and separating said layers one from the other.

3. Process of removing oil and color from an aqueous alcoholic solution of zein containing between 5% and 20% of water which comprises: treating said solution with a volatile aromatic hydrocarbon solvent for maize-oil and coloring matter in such quantity that the material is separated into two liquid layers, the lower containing zein, alcohol and some of the oil solvent, the upper layer containing oil, coloring matter, alcohol and oil solvent; and separating said layers one from the other.

4. Process of removing oil and color from an aqueous alcohol solution of zein which comprises:

' araaaer maize-oil and. coloring matter in such quantity that the material is separated into two liquid' that the material is separated into two liquid layers, the lower containing zein, its solvent and some toluol, the upper layer containing oil, coloring matter, some of the zein solvent and toluol; and separating said layers one from the other.

5. Process of removing oil and color from an aqueous alcohol solution of zein which comprises: treating the solution with benzol to dissolve the maize-oil and coloring matter in such quantity its solvent and oil, collayers, the lower containing zein, some benzol, the upper layer containing oring matter, some oi! thezein solvent and benzol;

and separating said layers one from the other.

6. Process of removing oil and color from an alcoholic solution of zein which comprises treating said solution with a solvent for maize-oil and coloring matter, which is at least partially miscible with alcohol, and is a non-solvent for zein, in such quantity that the material is separated into two liquid layers, the lower containing zein, its solvent, and some of the oil solvent, and the upper layer containing oil, coloring matter and zein and oil; and separating said layers one from the other.

LLOYD C. SWALLEN. 

